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Bureau of Mines Information Circular/1987 



Computer Modeling of the Effect 
of Mine-Fire-Induced Ventilation 
Disturbances on Stench Fire 
Warning System Performance 

By Linneas Laage, William Pomroy, and Thomas Weber 



UNITED STATES DEPARTMENT OF THE INTERIOR 




Information Circular 9154 



Computer Modeling of the Effect 
of Mine-Fire-Induced Ventilation 
Disturbances on Stench Fire 
Warning System Performance 

By Linneas Laage, William Pomroy, and Thomas Weber 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Donald Paul Hodel, Secretary 

BUREAU OF MINES 

David S. Brown, Acting Director 




no. ^s^ 



Library of Congress Cataloging in Publication Data: 



Laage, Linneas W. 

Computer modeling of the effect of mine-fire-induced ventilation 
disturbance on stench fire warning system performance. 

(Information circular; 9154) 

Bibliography: p. 12. 

Supt. of Docs, no.: I 28.27: 9154. 

1. Mine fires — Prevention and control— Mathematical models. 2. Mine fires — 
Prevention and control — Data processing. 3. Stench fire-warning system in mines — 
Mathematical models. 4. Stench fire-warning system in mines — Data processing. 5. Mine 
ventilation — Mathematical models. 6. Mine ventilation — Data processing. I. Pomroy, 
William H. II. Weber, Thomas. III. Title. rV. Series: Information circular (United States. 
Bureau of Mines); 9154. 

TN295.U4 [TN315] 622 s [622'.8] 87-600182 



CONTENTS 



Pa g e 



Abstract 1 

Introduction 2 

Operation of the stench warning computer model 2 

Case study analysis method 3 

Results of stench fire simulations 5 

Fire in branch 30 5 

Fire in branch 48 5 

Fire in branch 37 6 

Fire in branch 52 6 

Fire in branch 53 6 

Summary 12 

Conclusions 12 

References 12 

ILLUSTRATION 

1. Schematic of hypothetical mine ventilation network 4 

TABLES 

1. Physical characteristics of simulated fires 4 

Stench warning times under baseline conditions and under the influence of a 
fire in — 

2. Branch 30 7 

3. Branch 48 8 

4. Branch 37 9 

5. Branch 52 10 

6. Branch 53 11 







UNIT 


OF MEASURE ABBREVIATIONS 


USED 


IN THIS 


REPORT 


Btu/ft 3 






British thermal 
per cubic foot 


unit 






h 
in 


hour 
inch 


Btu/lb 






British thermal 
per pound 


unit 






lb/ft 3 


pound per cubic 
foot 


Btu/min 






British thermal 
per minute 


unit 






min 


minute 


Btu/(min* 


ft 2 


) 


British thermal 


unit 


per 




pet 


percent 








minute per square foot 






















ppb 


part per billion 


ft 3 /min 






cubic foot per 
minute 








yr 


year 



COMPUTER MODELING OF THE EFFECT OF MINE-FIRE-INDUCED 
VENTILATION DISTURBANCES ON STENCH FIRE WARNING SYSTEM 

PERFORMANCE 

By Linneas Laage, 1 William Pomroy, 2 and Thomas Weber 3 



ABSTRACT 

Underground mine fires can significantly influence mine ventilation 
airstreams, in some cases throttling or even reversing airflows. As a 
result, the performance of a metal and nonmetal mine stench fire warning 
system, which depends on the ventilation to carry the vital warning sig- 
nal, under fire conditions is different from performance under nonfire 
conditions. The safety of underground miners can be jeopardized if the 
warning signal is delayed. This Bureau of Mines report describes re- 
search to investigate fire and stench warning system interactions. A 
computer model is presented that permits quantitative analysis of stench 
warning signal delays as a function of fire location and intensity. The 
results of a case study involving computer simulations of stench distri- 
bution in a hypothetical mine network subject to various fire exposures 
are also discussed. This case study illustrates a technique for iden- 
tifying the areas within a mine that are subject to unacceptable warning 
signal delays, thereby enabling preemptive action by mine personnel, 
such as redeployment of stench injectors. 
_ 



Mining engineer. 
^Supervisory mining engineer. 
•^Engineering aid, computer science. 

Twin Cities Research Center, Bureau of Mines, Minneapolis, MN. 



INTRODUCTION 



Fires are an ever-present threat to the 
safety of underground miners. Since the 
smoke and toxic gas produced by a mine 
fire can be spread rapidly by the mine's 
ventilation system, mine evacuation must 
be accomplished as quickly as possible in 
the event of fire. In metal and nonmetal 
mines, the most common means of passing 
the fire warning signal to each miner is 
the stench system. The typical stench 
system utilizes ethyl raercaptan, a highly 
odoriferous organic compound, injected on 
the surface into the compressed and/or 
ventilation airstreams. Upon smelling 
the stench, workers evacuate the mine ac- 
cording to an emergency preplan. 

Although the stench system has been 
used successfully for over 60 yr, it has 
several serious shortcomings, owing to 
certain chemical properties of ethyl raer- 
captan and to certain performance char- 
acteristics and limitations of present 
injection systems. 

Recent Bureau research succeeded in up- 
grading the overall safety and effective- 
ness of the stench system through the use 
of a superior stench odorant and the de- 
velopment of improved stench injection 
equipment ^1_). 4 This research has also 
investigated a specialized computer simu- 
lation model capable of calculating the 
precise concentration of stench in any 
mine ventilation network branch at any 
time after stench release (2^)« An 
adaptation of the computer model now 
enables the analysis of stench system and 
ventilation system interactions under the 
influence of a mine fire. 

Mine fires, depending on their location 
and intensity, can significantly change 
ventilation flows. The heat energy from 



the fire can throttle or even reverse the 
direction of airflows in large areas of a 
mine. Under such conditions, the stench 
odor may not be carried by the ventila- 
tion streams to all parts of a mine in 
time to permit a safe mine evacuation, 
even though satisfactory stench distribu- 
tion is achieved during routine fire 
drills. In these cases, fire drills only 
serve to reinforce the false security 
provided by such a system. Ironically, 
the circumstances resulting in degraded 
warning system performance exist only 
during an actual fire emergency. A 
problem arises in that the interactions 
between a fire and a stench warning 
system are highly complex — so complex 
that conventional analytic techniques for 
designing stench systems do not address 
fire effects. 

Use of the stench fire warning system 
computer model will enable mine safety 
officials to quantitatively analyze 
stench system performance under simulated 
fire conditions. The program calculates 
stench odor transport time to each mine 
network branch as a function of fire 
intensity and location. Preemptive 
action, such as relocation of stench 
injectors, is indicated if the fire- 
induced ventilation changes result in 
excessive stench transport times to key 
work areas. 

This Bureau of Mines report briefly 
describes the operation of the program 
and illustrates its use through a case 
study analysis of stench distribution in 
a hypothetical 53-branch mine ventilation 
network under both baseline (nonfire) and 
mine fire conditions. 



OPERATION OF THE STENCH WARNING COMPUTER MODEL 



The stench warning model is evaluated 
with a ventilation network analysis com- 
puter program developed under contract 
for the Bureau by Michigan Technological 
University. 

^Underlined numbers in parentheses re- 
fer to items in the list of references at 
the end of this report. 



Ventilation calculations are made with- 
in the program, which represents the mine 
network as a collection of closed paths 
or meshes. The mine network and operat- 
ing conditions are described in an input 
data file. At each junction (airway 
intersection within the mine network), 
conservation of mass is applied to relate 
the airflow rates. The conservation of 



energy is applied to the airflow around 
each mesh, with frictional wall losses 
being used to establish pressure losses 
along airways. As part of the energy 
balance calculation, temperature and 
elevation variations within the mine are 
used to calculate natural ventilation 
pressures, and fan pressures are deter- 
mined from the fan characteristic data. 
The conservation of mass and energy 
equations are solved iteratively until 
the airflow rates are balanced throughout 
the mine network. 

The localized heat production rate of 
the fire is entered as part of the input 
data to the program. The heat addition 
alters the airflow, and its effect is 
evaluated by calculating the new tempera- 
ture distribution and airflow rates. The 
real-time capability of the program is 
utilized to project the time-dependent 



spread of stench from a warning system 
throughout the mine complex. This evalu- 
ation proceeds by associating control 
volumes with specific stench concentra- 
tions. Each control volume is trans- 
ported with the airflow. At junctions 
where control volumes meet, perfect mix- 
ing is assumed and a new control volume 
(a new stench concentration) is formed. 
The stench injector locations and fire 
locations are specified in the network, 
as are the duration of the injection 
period and the duration and intensity of 
the fires. Changes in the ventilation 
system (addition of network branches, 
etc. ) and events related to the occur- 
rence of a fire (shutdown of underground 
fans, etc.) can easily be accommodated by 
revising the input data file. Utiliza- 
tion and operation of the computer model 
have been described previously (3-7). 



CASE STUDY ANALYSIS METHOD 



The effect of mine fires on the distri- 
bution of stench odor in an underground 
mine network was analyzed through com- 
puter simulation. The subject of the 
simulations was a hypothetical 53-branch 
mine ventilation network. A schematic 
representation of the network, indicating 
fan locations, stench injector locations, 
and airway numbers, is shown in 
figure 1. 

The case study involved the analysis of 
five fires. To simplify the analysis, 
the fires were assumed to be diesel fuel 
pool fires. The fires achieved steady- 
state burning almost immediately, with 
essentially no incipient stage heating 
and no change in intensity over time. 
The diesel fuel pools en be visualized as 
circular, of sufficient surface area to 
produce a fire of the maximum intensity 
for the available oxygen, and of suf- 
ficient depth to burn for 1 h. The maxi- 
mum fire size was determined by the sim- 
plified combustion relationship (8): 

C + 2 ♦ C0 2 + 470 Btu/ft 3 2 

with all available 2 converted com- 
pletely to C0 2 until a residual level of 
9 pet 2 is reached. The analysis is 



based on a burning rate of 0.12 in of 
fuel depth per minute, a fuel density of 
61 lb/ft 3 , and a heat release of 19,390 
Btu/lb, yielding a heat release rate of 
11,830 Btu/(min*f t 2 ) of fuel surface area 
(90. The physical characteristics of the 
simulated fires are shown in table 1. 

As the smoke and gases produced by the 
fires were not of principal interest, and 
their presence in the network would only 
confound the analysis of stench distri- 
bution, the fires were modeled as sources 
of heat with no generation of smoke or 
gases. Conversely, the injection of 
stench gas was modeled as a source of 
fume contaminant without heat release. 

Stench injection was started 10 min 
after each fire was initiated and con- 
tinued for 10 min thereafter. The de- 
tection threshold of the stench odor was 
assumed to be 10 ppb (ability to detect 
the odor varies with age, sex, state of 
health, and other factors, and ranges 
from under 2 ppb to 120 ppb in extreme 
cases). Stench injection rate was con- 
stant in all simulations at 0.0706 
ft 3 /min. Stench injector locations were 
selected based on standard industry 
practice: atop downcast ventilation 
shafts. 




KEY 

Airway 

Airway number 

Airflow direction 

Junction 

Surface junction 

Vertical shaft or 

winze 

Stench injector 



FIGURE 1. — Schematic ot hypothetical mine ventilation network. 
TABLE 1. - Physical characteristics of simulated fires 



Simulation 


Fire location 


Pool diam, 


Fire intensity, 


Airflow, 




airway 


ft 


Btu/min 


f t 3 /min 


1 and 2. . . 


30 


12.40 


1,375,500 


26,230 


3 and 4. . . 


48 


22.19 


4,401,400 


83,933 


5 and 6. . . 


37 


17.96 


2,882,600 


54,969 


7 and 8. . . 


52 


26.08 


6,081,300 


115,966 


9 and 10.. 


53 


4.32 


166,700 


3, 179 



RESULTS OF STENCH FIRE SIMULATIONS 



As noted above, the case study involved 
an analysis of five fires. For each 
fire, two simulations were performed — 
one with both surface and underground 
mine fans operating and one with the 
underground fan shut down (as sometimes 
occurs during actual mine fires). Warn- 
ing times to each network branch were 
then calculated for each fan and fire 
condition and tabulated. The warning 
time is the shortest time required for 
the stench to travel from any injector to 
the end of a given branch. The maximum 
acceptable warning time was arbitrarily 
chosen as 60 min. A baseline stench 
distribution simulation was performed to 
confirm that nonfire warning times met 
the acceptance criteria and to provide a 
basis for comparing warning times calcu- 
lated under fire conditions. The maximum 
baseline warning time was 55.64 min, with 
an average time of 28.05 min and a mini- 
mum of 13.44 min. Airway reversals and 
warning times that exceeded the accept- 
able maximum are also indicated in tables 
2-6, which are grouped at the end of the 
text discussion. 

FIRE IN BRANCH 30 

Stench warning times under baseline 
conditions and under the influence of a 
fire in branch 30 are shown in table 2. 
The ^,375,000-Btu/min fire in branch 30, 
a horizontal drift, had the effect of re- 
ducing maximum and average warning times 
slightly for both fan conditions. With 
the underground fan shut down, the maxi- 
mum warning time was 52.17 min, the 
average was 26.42 min, and the minimum 
was 13.33 min. The average reduction in 
warning time was 1.63 min, or about 5.8 
pet. With both fans operating, the maxi- 
mum warning time was 53.58 min, the 
average was 27.89 min, and the minimum 
was 13.45 min. The average reduction in 
warning time was 0.16 min, or about 0.5 
pet. Although warning time delays rang- 
ing to 18.27 min were produced by the 



fire, the acceptable maximum warning time 
was not exceeded in any branch under 
either fan condition. Airflow reversals 
occurred in branches 20 and 53 with the 
underground fan shut down. 

FIRE IN BRANCH 48 

Stench warning times under baseline 
conditions and under the influence of a 
fire in branch 48 are shown in table 3. 
The 4,401,400-Btu/min fire in branch 48, 
a horizontal drift intersecting a verti- 
cal shaft with airflow toward the upcast 
shaft, had the effect of increasing the 
maximum and average warning times 
slightly for both fan conditions. With 
the underground fan shut down, the maxi- 
mum warning time was 57.08 min, the 
average was 28.30 min, and the minimum 
was 13.43 min. The average warning time 
delay was 0.24 min, or about 0.87 pet. 
With both fans operating, the maximum 
warning time was 66.88 min, the average 
was 30.80 min, and the minimum was 13.57 
min. The average warning time delay was 
2.75 min, or about 9.80 pet. Warning 
time delays ranged to 21.25 min with the 
underground fan shut down and 24.6 min 
with both fans operating. With the 
underground fan shut down, the maximum 
acceptable warning time was not exceeded; 
however, with both fans operating, the 
maximum acceptable warning time was ex- 
ceeded in two branches — 20 and 32. The 
warning times in those branches were 
65.96 and 66.88 min respectively, or 
about 20.2 and 59.5 pet above the base- 
line warning times. In both cases, the 
warning signal reached the beginning of 
the branch within the prescribed 60 min 
(36.94 and 48.24 min respectively); how- 
ever, the air velocity was too slow to 
carry the signal to the end of the branch 
in time. In one case, branch 20, an air 
reversal occurred. Another air reversal 
was noted in branch 53, which is a 
continuation of branch 20. 



FIRE IN BRANCH 37 

Stench warning times under baseline 
conditions and under the influence of a 
fire in branch 37 are shown in table 4. 
The 2,882,600-Btu/min fire in branch 37, 
a horizontal drift, had the effect of 
reducing maximum and average warning 
times slightly for both fan conditions. 
With the underground fan shut down, the 
maximum warning time was 51.23 min, the 
average was 26.25 min, and the minimum 
was 13.34 min. The average reduction in 
warning time was 1.80 min, or about 6.4 
pet. With both fans operating, the maxi- 
mum warning time was 55.03 min, the 
average was 27.66 min, and the minimum 
was 13.44 min. The average reduction in 
warning time was 0.30 min, or about 1.1 
pet. Although warning time delays rang- 
ing to 17.33 min were produced by the 
fire, the acceptable maximum warning time 
was not exceeded in any branch under 
either fan condition. Air reversals oc- 
curred in branches 20 and 53 with the 
underground fan shut down. 

FIRE IN BRANCH 52 

Stench warning times under baseline 
conditions and under the influence of a 
fire in branch 52 are shown in table 5. 
The 6,081,300-Btu/min fire in branch 52, 
a vertical shaft, had the effect of re- 
ducing the average warning time slightly 
when the underground fan was shut down 
and increasing the average warning time 
slightly when both fans were operating, 
but significantly increasing the maximum 
warning time under both fan conditions. 
With the underground fan shut down, the 
maximum warning time was 110.10 min, the 
average was 27.01 min, and the minimum 
was 11.29 min. The average reduction in 
warning time was 1.04 min, or about 3.71 
pet; however, warning time delays ranged 
to 87.41 min, or nearly 400 pet of the 
baseline. With both fans operating, the 
maximum warning time was 124.59 min, the 
average was 28.26 min, and the minimum 
was 11.28 min. The average warning time 
delay was 0.21 min, or about 0.7 pet; 



however, delays ranging to over 80 min, 
or nearly 400 pet, were produced. 
Numerous reversals occurred as well, as 
shown in table 5, including branch 3, 
which is a downcast ventilation shaft and 
therefore the site of a stench injector. 
With the reversal of branch 3, stench 
from that injector is exhausted to the 
surface and is lost. With the under- 
ground fan shut down, the acceptable 
maximum warning time was exceeded in 
three branches. With both fans operat- 
ing, the maximum was exceeded in five 
branches. 

FIRE IN BRANCH 53 

Stench warning times under baseline 
conditions and under the influence of a 
fire in branch 53 are shown in table 6. 
The relatively small 166, 700-Btu/min fire 
in branch 53, a vertical winze, had the 
effect of reducing the average warning 
times slightly under both fan conditions, 
but increasing the maximum warning times 
when the underground fan was shut down. 
With the underground fan shut down, the 
maximum warning time was 66.15 min — a 95- 
pct increase over the baseline. The 
average warning time was 26.79 min, and 
the maximum was 13.28 min. The average 
warning time reduction was 1.26 min, or 
about 4.49 pet. With both fans operat- 
ing, the maximum warning time was 51.38 
min, the average was 26.23 min, and the 
minimum was 13.31 min. The average 
reduction in warning time was 1.82 min, 
or about 6.49 pet. With the underground 
fan shut down, warning time reductions of 
over 17 min occurred; however, delays of 
up to 32.25 min were also produced. With 
both fans operating, warning time re- 
ductions ranging to 15.41 min occurred 
while delays were limited to 5.5 min or 
less. Only with the underground fan shut 
down was the acceptable maximum warning 
time exceeded. It occurred in only one 
branch by only 6.15 min. Under both fan 
conditions, air reversals occurred in 
branches 20 and 53. (The fire was in 53, 
and 20 is a continuation of that branch.) 



TABLE 2. - Stench warning times under baseline conditions and under the influence of a 
fire in branch 30 







Fan in branch 


Fans in branches 




Baseline 
warning 


51 only 


6 and 51 


Airway 


Warning 


Difference 


Warning 


Difference 




time, min 


time, min 


from baseline, 
min 


time, min 


from baseline, 
min 


1 


13.44 


13.33 


-0.11 


13.45 


-0.01 


2 


14.97 


14.48 


-.49 


14.97 


.00 


3 


14.45 


15.02 


.57 


14.47 


.02 


4 


29.84 


26.98 


-2.86 


28.95 


-.89 


5 


20.84 


25.81 


4.97 


20.87 


.03 


6 


14.64 


15.34 


.70 


14.66 


.02 


7 


18.32 


22.41 


4.09 


18.35 


.03 


8 


33.90 


52.17 


18.27 


34.00 


.10 


9 


20.77 


27.13 


6.36 


20.81 


.04 


10 


22.97 


31.35 


8.38 


23.02 


.05 


11 


29.37 


36.26 


6.89 


29.41 


.04 


12 


20.01 


18.27 


-1.74 


19.97 


-.04 


13 


31.42 


27.72 


-3.70 


30.51 


-.91 


14 


21.66 


19.46 


-2.20 


21.68 


.02 


15 


23.61 


20.85 


-2.76 


23.69 


.08 


16 


34.76 


28.81 


-5.95 


35.18 


.42 


17 


27.91 


23.92 


-3.99 


28.12 


.21 


18 


29.45 


25.02 


-4.43 


29.71 


.26 


19 


31.37 


26.39 


-4.98 


31.69 


.32 


20 


41.36 


'29.35 


-12.01 


43.65 


2.29 


21 


32.93 


29.64 


-3.29 


33.32 


.39 


22 


30.31 


25.97 


-4.34 


30.59 


.28 


23 


31.79 


28.47 


-3.32 


32.14 


.35 


24 


30.70 


26.96 


-3.74 


31.30 


.60 


25 


32.60 


29.40 


-3.20 


33.27 


.67 


26 


33.17 


30.01 


-3.16 


33.85 


.68 


27 


50.32 


34.43 


-15.89 


44.59 


-5.73 


28 


35.00 


31.05 


-3.95 


33.88 


-1.12 


29 


32.39 


28.48 


-3.91 


31.37 


-1.02 


30 


48.33 


42.17 


-6.16 


45.89 


-2.44 


31 


45.06 


40.01 


-5.05 


43.49 


-1.57 


32 


55.64 


49.04 


-6.60 


53.58 


-2.06 


33 


40.75 


36.32 


-4.43 


38.37 


-1.38 


34 


40.75 


36.32 


-4.43 


39.37 


-1.38 


35 


16.67 


17.19 


.52 


16.69 


.02 


36 


22.74 


23.12 


.38 


22.77 


.03 


37 


21.33 


21.73 


.40 


21.35 


.02 


38 


18.40 


18.24 


-.16 


18.42 


.02 


39 


25.12 


24.85 


-.27 


25.14 


.02 


40 


27.36 


27.63 


.27 


27.40 


.04 


41 


31.93 


32.11 


.18 


31.98 


.05 


42 


47.01 


46.75 


-.26 


47.05 


.04 


43 


18.07 


17.91 


-.16 


18.09 


.02 


44 


19.46 


19.27 


-.19 


19.48 


.02 


45 


19.85 


19.66 


-.19 


19.87 


.02 


46 


14.54 


14.41 


-.13 


14.55 


.01 


47 


14.81 


14.69 


-.12 


14.82 


.01 


48 


37.03 


33.98 


-3.05 


37.67 


.64 


49 


16.20 


16.10 


-.10 


16.21 


.01 


51 


16.23 


16.12 


-.11 


16.24 


.01 


52 


14.51 


15.08 


.57 


14.52 


.01 


53 


42.47 


'26.56 


-15.91 


44.91 


2.44 


Air revei 


•sal occurred. 











TABLE 3. - Stench warning times under baseline conditions and under the influence of a 
fire in branch 48 







Fan in branch 


Fans in branches 




Baseline 
warning 


51 only 


6 


and 51 


Airway 


Warning 


Difference 


Warning 


Difference 




time, min 


time, min 


from baseline, 
min 


time, min 


from baseline, 
min 


1 


13.44 


13.43 


-0.01 


13.57 


0.13 


2 


14.97 


14.76 


-.21 


15.45 


.48 


3 


14.45 


15.04 


.59 


14.44 


-.01 


4 


29.84 


30.46 


.62 


34.68 


4.84 


5 


20.84 


24.75 


3.91 


20.55 


-.29 


6 


14.64 


15.39 


.75 


14.63 


-.01 


7 


18.32 


23.03 


4.71 


18.41 


.09 


8 


33.90 


55.15 


21.25 


34.42 


.52 


9 


20.77 


28.14 


7.37 


20.93 


.16 


10 


22.97 


32.71 


9.74 


23.19 


.22 


11 


29.37 


36.91 


7.54 


29.19 


-.18 


12 


20.01 


19.14 


-.87 


21.63 


1.62 


13 


31.42 


31.23 


-.19 


36.50 


5.08 


14 


21.66 


20.47 


-1.19 


23.61 


1.95 


15 


23.61 


22.01 


-1.60 


25.93 


2.32 


16 


34.76 


30.85 


-3.91 


39.23 


4.47 


17 


27.91 


25.42 


-2.49 


31.06 


3.15 


18 


29.45 


26.64 


-2.81 


32.90 


3.45 


19 


31.37 


28.16 


-3.21 


35.19 


3.82 


20 


41.36 


'30.46 


-10.90 


'' 2 65.96 


24.60 


21 


32.93 


39.31 


6.38 


37.52 


4.59 


22 


30.31 


27.72 


-2.59 


34.02 


3.71 


23 


31.79 


33.00 


1.21 


36.17 


4.38 


24 


30.70 


29.06 


-1.64 


35.76 


5.06 


25 


32.60 


32.81 


.21 


38.42 


5.82 


26 


33.17 


33.62 


.45 


39.18 


6.01 


27 


50.32 


37.89 


-12.43 


52.93 


2.61 


28 


35.00 


35.73 


.73 


41.18 


6.18 


29 


32.39 


32.24 


-.15 


37.72 


5.33 


30 


48.33 


49.53 


1.20 


57.67 


9.34 


31 


45.06 


46.15 


1.09 


53.60 


8.54 


32 


55.64 


57.08 


1.45 


2 66. 88 


11.24 


33 


40.75 


41.71 


.96 


48.24 


7.49 


34 


40.75 


41.71 


.96 


48.24 


7.49 


35 


16.67 


17.13 


.46 


16.57 


-.10 


36 


22.74 


22.81 


.07 


22.37 


-.37 


37 


21.33 


21.48 


.15 


21.03 


-.30 


38 


18.40 


18.14 


-.26 


18.32 


-.08 


39 


25.12 


24.64 


-.48 


24.92 


-.20 


40 


27.36 


27.14 


-.22 


26.79 


-.57 


41 


31.93 


31.40 


-.53 


31.14 


-.79 


42 


47.01 


46.32 


-.69 


46.52 


-.49 


43 


18.07 


17.83 


-.24 


18.00 


-.07 


44 


19.46 


19.12 


-.34 


19.32 


-.14 


45 


19.85 


19.49 


-.36 


19.70 


-.15 


46 


14.54 


14.47 


-.07 


14.62 


.08 


47 


14.81 


14.77 


-.04 


14.92 


.11 


48 


37.03 


38.95 


1.92 


44.31 


7.28 


49 


16.20 


16.23 


.03 


16.36 


.16 


51 


16.23 


16.25 


.02 


16.39 


.16 


52 


14.51 


15.10 


.59 


14.49 


-.02 


53 


42.47 


'28.29 


-14.18 


'36.94 


-5.53 



Air reversal occurred. 



Exceeded acceptable maximum. 



TABLE 4. - Stench warning times under baseline conditions and under the influence of a 
fire in branch 37 







Fan 


in branch 


Fans in branches 




Baseline 
warning 


51 only 


6 and 51 


Airway 


Warning 


Difference 


Warning 


Difference 




time, rain 


time, min 


from baseline, 
min 


time, min 


from baseline, 
min 


1 


13.44 


13.34 


-0.10 


13.44 


0.00 


2 


14.97 


14.48 


-.49 


14.94 


-.03 


3 


14.45 


15.17 


.72 


14.61 


.16 


4 


29.84 


27.25 


-2.59 


29.57 


-.27 


5 


20.84 


28.35 


7.51 


21.56 


.72 


6 


14.64 


15.49 


.85 


14.80 


.16 


7 


18.32 


22.34 


4.02 


18.45 


.13 


8 


33.90 


51.23 


17.33 


33.93 


.03 


9 


20.77 


26.92 


6.15 


20.89 


.12 


10 


22.97 


31.02 


8.05 


23.07 


.10 


11 


29.37 


36.01 


6.64 


29.39 


.02 


12 


20.01 


18.25 


-1.76 


19.89 


-.12 


13 


31.42 


28. 13 


-3.29 


31.12 


-.30 


14 


21.66 


19.42 


-2.24 


21.51 


-.15 


15 


23.61 


20.77 


-2.84 


23.42 


-.19 


16 


34.76 


28.54 


-6.22 


34.36 


-.40 


17 


27.91 


23.77 


-4.14 


27.64 


-.27 


18 


29.45 


24.84 


-4.61 


29.15 


-.30 


19 


31.37 


26.18 


-5.19 


31.04 


-.33 


20 


41.36 


'29.18 


-12.18 


42.97 


1.61 


21 


32.93 


29.16 


-3.77 


32.58 


-.35 


22 


30.31 


25.77 


-4.54 


30.01 


-.30 


23 


31.79 


28.10 


-3.69 


31.48 


-.31 


24 


30.70 


26.60 


-4.10 


30.38 


-.32 


25 


32.60 


28.92 


-3.68 


32.26 


-.34 


26 


33.17 


29.51 


-3.66 


32.82 


-.35 


27 


50.32 


35.30 


-15.02 


49.54 


-.78 


28 


35.00 


31.60 


-3.40 


34.65 


-.35 


29 


32.39 


28.97 


-3.42 


32.07 


-.32 


30 


48.33 


43.33 


-5.00 


47.82 


-.51 


31 


45.06 


40.49 


-4.57 


44.59 


-.47 


32 


55.64 


49.66 


-5.98 


55.03 


-.61 


33 


40.75 


36.74 


-4.01 


40.34 


-.41 


34 


40.75 


36.74 


-4.01 


40.34 


-.41 


35 


16.67 


17.53 


.86 


17.02 


.35 


36 


22.74 


22.79 


.05 


22.40 


-.34 


37 


21.33 


23.20 


1.87 


22.86 


1.53 


38 


18.40 


18.08 


-.32 


18.24 


-.16 


39 


25.12 


25.19 


.07 


25.47 


.35 


40 


27.36 


26.79 


-.57 


26.50 


-.86 


41 


31.93 


31.40 


-.53 


31.22 


-.71 


42 


47.01 


35.49 


-11.52 


35.37 


-11.64 


43 


18.07 


17.71 


-.36 


17.86 


-.21 


44 


19.46 


19.28 


-.18 


19.48 


.02 


45 


19.85 


19.68 


-.17 


19.89 


.04 


46 


14.54 


14.40 


.14 


14.52 


-.02 


47 


14.81 


14.68 


-.13 


14.80 


-.01 


48 


37.03 


33.43 


-3.60 


36.63 


-.40 


49 


16.20 


16.11 


-.09 


16.21 


.01 


51 


16.23 


16.14 


-.09 


16.23 


.00 


52 


14.51 


15.23 


.72 


14.66 


.15 


53 


42.47 


'26.35 


-16.12 


44.17 


1.70 


'Air rever 


sal occurred. 











10 



TABLE 5. - Stench warning times under baseline conditions and under the influence of a 
fire in branch 52 







Fan in branch 


Fans in branches 




Baseline 
warning 


51 


only 


6 


and 51 


Airway 


Warning 


Difference 


Warning 


Difference 




time, min 


time, min 


from baseline, 
min 


time, min 


from baseline, 
min 


1 


13.44 


11.29 


-2.15 


11.28 


-2.16 


2 


14.97 


12.01 


-2.96 


11.97 


-3.00 


3 


14.45 


'11.75 


-2.70 


1 11.72 


-2.73 


4 


29.84 


19.79 


-10.05 


19.53 


-10.31 


5 


20.84 


12.43 


-8.41 


12.44 


-8.40 


6 


14.64 


'31.71 


17.07 


'27.17 


12.53 


7 


18.32 


'31.52 


13.20 


'27.05 


8.73 


8 


33.90 


'44.90 


11.00 


'35.82 


1.92 


9 


20.77 


'26.35 


5.58 


'23.64 


2.87 


10 


22.97 


'22.93 


-0.04 


'21.38 


-1.59 


11 


29.37 


28.79 


-0.58 


31.38 


2.01 


12 


20.01 


14.39 


-5.62 


14.23 


-5.78 


13 


31.42 


21.85 


-9.57 


21.34 


-10.08 


14 


21.66 


15.09 


-6.57 


14.89 


-6.77 


15 


23.61 


15.89 


-7.72 


15.65 


7.96 


16 


34.76 


20.49 


-14.27 


20.00 


-14.76 


17 


27.91 


17.66 


-10.25 


17.33 


-10.58 


18 


29.45 


18.30 


-11.15 


17.93 


-11.52 


19 


31.37 


19.09 


-12.28 


'18.68 


-12.69 


20 


41.36 


'19.85 


-21.51 


'19.34 


-22.02 


21 


32.93 


'20.83 


-12.10 


19.94 


-12.99 


22 


30.31 


18.92 


-11.39 


'18.54 


-11.77 


23 


31.79 


'22.99 


-8.80 


21.26 


-10.53 


24 


30.70 


19.32 


-11.38 


18.94 


-11.76 


25 


32.60 


25.89 


-6.71 


32.12 


-.48 


26 


33.17 


24.99 


-8.18 


24.35 


-8.82 


27 


50.32 


24.38 


-25.94 


23.68 


-26.64 


28 


35.00 


24.59 


-10.41 


24.09 


-10.91 


29 


32.39 


22.37 


-10.02 


21.85 


-10.54 


30 


48.33 


28.92 


-19.41 


28.42 


-19.91 


31 


45.06 


27.30 


-17.76 


26.85 


-18.21 


32 


55.64 


32.48 


-23. 16 


31.89 


-23.75 


33 


40.75 


25. 17 


-15.58 


24.77 


-15.98 


34 


40.75 


25.17 


-15.58 


24.7 7 


-15.98 


35 


16.67 


'39.60 


22.93 


2 80. 60 


63.93 


36 


22.74 


'» 2 110.10 


87.41 


2 69.44 


46.70 


37 


21.33 


'29.60 


8.27 


'37.99 


16.66 


38 


18.40 


15.88 


-2.52 


1 15.73 


-2.67 


39 


25. 12 


32.93 


7.81 


'30.83 


5.71 


40 


27.36 


'' 2 102.33 


74.97 


2 94. 12 


66.76 


41 


31.93 


2 101.54 


69.61 


2 112.80 


80.87 


42 


47.01 


'39.14 


-7.87 


2 124. 59 


77.58 


43 


18.07 


14.63 


-3.44 


14.72 


-3.35 


44 


19.46 


20.98 


1.52 


1 19.62 


.16 


45 


19.85 


24.30 


4.45 


21.24 


1.39 


46 


14.54 


12. 18 


-2.36 


12. 18 


-2.36 


47 


14.81 


12.59 


-2.22 


12.56 


-2.25 


48 


37.03 


28.30 


-8.73 


27.97 


-9.06 


49 


16.20 


14.71 


-1.49 


14.68 


-1.52 


51 


16.23 


14.74 


-1.49 


14.72 


-1.51 


52 


14.51 


'12.44 


-2.07 


'12.45 


-2.06 


53 


42.47 


'19.13 


-23.34 


'18.72 


-23.75 



Air reversal occurred. 



Exceeded acceptable maximum. 



11 



TABLE 6. - Stench warning times under baseline conditions and under the influence of a 
fire in branch 53 







Fan in branch 


Fans . 


n branches 




Baseline 
warning 


51 only 


6 


and 51 


Airway 


Warning 


Difference 


Warning 


Difference 




time, min 


time, min 


from baseline, 
min 


time, min 


from baseline, 
min 


1 


13.44 


13.28 


-0.16 


13.31 


-0. 13 


2 


14.97 


14.33 


-.64 


14.52 


-.45 


3 


14.45 


15.18 


.73 


14.71 


.26 


4 


29.84 


26.45 


-3.39 


28.00 


-1.84 


5 


20.84 


30.44 


9.60 


22.76 


1.92 


6 


14.64 


15.68 


1.04 


14.94 


.30 


7 


18.32 


25.38 


7.06 


19.63 


1.31 


8 


33.90 


1 66. 15 


32.25 


2 39.48 


5.58 


9 


20.77 


31.92 


11.15 


22.76 


1.99 


10 


22.97 


37.77 


14.80 


25.57 


2.60 


11 


29.37 


33.07 


3.70 


31.14 


1.77 


12 


20.01 


17.78 


-2.23 


18.52 


-1.49 


13 


31.42 


27.20 


-4.22 


28.93 


-2.49 


14 


21.66 


18.33 


-3.33 


18.76 


-1.90 


15 


23.61 


20.05 


-3.56 


21.20 


-2.41 


16 


34.76 


27.04 


-7.72 


29.46 


-5.30 


17 


27.91 


22.75 


-5.16 


24.39 


-3.52 


18 


29.45 


23.71 


-5.74 


25.53 


-3.92 


19 


31.37 


24.92 


-6.45 


26.95 


-4.42 


20 


41.36 


2 26. 59 


-14.77 


2 29.93 


-11.43 


21 


32.93 


32.00 


-.93 


29.80 


-3.13 


22 


30.31 


24.59 


-5.72 


26.50 


-3.81 


23 


31.79 


28.38 


-3.41 


28.80 


-2.99 


24 


30.70 


25.42 


-5.28 


27.39 


-3.31 


25 


32.60 


28.24 


-4.36 


29.75 


-2.85 


26 


33.17 


28.87 


-4.30 


30.35 


-2.82 


27 


50.32 


32.69 


-17.63 


36.74 


-13.58 


28 


35.00 


30.73 


-4.27 


32.54 


-2.46 


29 


32.39 


28.01 


-4.38 


29.81 


-2.58 


30 


48.33 


41.78 


-6.55 


44.77 


-3.46 


31 


45.06 


39.06 


-6.00 


41.80 


-3.26 


32 


55.64 


47.80 


-7.84 


51.38 


-4.26 


33 


40.75 


35.49 


-5.26 


37.89 


-2.86 


34 


40.75 


35.49 


-5.26 


37.89 


-2.86 


35 


16.67 


17.35 


.68 


16.94 


.27 


36 


22.74 


23.26 


.52 


23.03 


.29 


37 


21.33 


21.87 


.54 


21.61 


.28 


38 


18.40 


18.20 


-.20 


18.33 


-.07 


39 


25.12 


24.82 


-.30 


25.12 


.00 


40 


27.36 


27.66 


.40 


27.67 


.31 


41 


31.93 


32.22 


.29 


32.27 


.34 


42 


47.01 


46.91 


-.10 


47.42 


.41 


43 


18.07 


17.87 


-.20 


18.00 


-.07 


44 


19.46 


19.23 


-.23 


19.40 


-.06 


45 


19.85 


19.61 


-.24 


19.79 


-.06 


46 


14.54 


14.37 


-.17 


14.42 


-.12 


47 


14.81 


14.65 


-.16 


14.70 


-.11 


48 


37.03 


45.98 


8.95 


34.43 


-2.60 


49 


16.20 


16.05 


-.15 


16.08 


-.12 


51 


16.23 


16.08 


-.15 


16.10 


-.13 


52 


14.51 


15.24 


.73 


14.76 


.25 


53 


42.47 


2 24. 99 


-17.48 


2 27.06 


-15.41 


'Exceeded 


acceptable raaximi 


am. 2 Air re vers 


al occurred. 







4388 94 



12 



SUMMARY 



Through computer simulation and case 
study analysis, the effect of various 
fires on the performance of a typical 
mine stench fire warning system was 
studied. The predominant effect observed 
was to reduce warning times slightly to 
most areas; however, in each case 
studied, significant warning time delays 
occurred, often ranging to over 1 h. The 
longest delays occurred as a result 
of shaft fires; however, warning times 



exceeding the target maximum of 1 h were 
also produced by drift fires. Fire lo- 
cation was shown to be a critical factor. 
Even though the fire in airway 53 had an 
intensity of only 4 to 12 pet of the 
fires in airways 30, 37, and 48, it pro- 
duced comparable maximum and minimum 
delay times. Lengthy warning times 
delays were frequently, but not always, 
associated with airflow reversals. 



CONCLUSIONS 



An effective and reliable fire warning 
system is an essential element of every 
mine's fire emergency preplan. In metal 
and nonmetal mines, the most common means 
of fire warning is the stench sys- 
tem. However, this study illustrates 
the inherent tendency of stench 
systems to perform differently under 
fire conditions than during routine 
fire drills. Unless these differences 
are known, and suitable precautions 
against a warning system failure 



are implemented, disastrous consequences 
can result. 

The computer model presented in this 
report is recommended as an efficient and 
accurate tool for quantitatively analyz- 
ing stench system performance under both 
fire and nonfire conditions, and evaluat- 
ing the effectiveness of potential reme- 
dial actions, such as injector reloca- 
tion. Specific questions on modeling 
techniques should be referred to the 
authors. 



REFERENCES 



1. Pomroy, W. H. , and T. L. Muldoon. 
Improved Stench Fire Warning "for Under- 
ground Mines. BuMines IC 9016, 1985, 
33 pp. 

2. Ouderkirk, S. J., W. H. Pomroy, 
J. C. Edwards, and J. Marks. Mine Stench 
Fire Warning Computer Model Development 
and In-Mine Validation Testing. Paper in 
Proceedings of 2nd U.S. Mine Ventilation 
Symposium, (Univ. of NV-Reno, Reno, NV, 
Sept. 23-25, 1985), A. A. Balkema, 1985, 
pp. 29-35. 

3. Edwards, J. C. , and R. E. Greuer. 
Real-Time Calculation of Product- 
of-Combustion Spread in a Multilevel 
Mine. BuMines IC 8901, 1982, 117 pp. 

4. Edwards, J. C, and J. S. Li. Com- 
puter Simulation of Ventilation in Multi- 
level Mines. Paper in Proceedings of 3rd 
International Mine Ventilation Congress 
(Harrogate, England, June 13-19, 1984). 
Inst. Min. and Metall. , 1984, pp. 47-51. 

5. Greuer, R. E. Real-Time Precalcu- 
lations of the Distribution of Combustion 



Products and Other Contaminants in the 
Ventilation System of Mines (contract 
J0285002, MI Technol. Univ.). BuMines 
OFR 22-82, 1981, 263 pp.; NTIS PB 82- 
183104. 

6. . Study of Mine Fires and 

Mine Ventilation. Part I. Computer Sim- 
ulation of Ventilation Systems Under the 
Influence of Mine Fires (contract 
S0241032, MI Technol. Univ.). BuMines 
OFR 115(l)-78, 1977, 165 pp.; NTIS PB 288 
231/AS. 

7. . A Study of Precalculation 

of the Effect of Fires on Ventilation 
Systems of Mines (contract J0285002, MI 
Technol. Univ.). BuMines OFR 19-84, 
1983, 293 pp.; NTIS PB 84-159979. 

8. Baumeister, T. , and L. S. Marks 
(eds.). Standard Handbook for Mechanical 
Engineers. McGraw-Hill, 7th ed. , 1967, 
pp. 4-72. 

9. Drysdale, D. An Introduction to 
Fire Dynamics. Wiley, 1985, pp. 152-185. 



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